Power system for firearms



March 21, 1961 0. c. FLETCHER POWER SYSTEM FOR FIREARMS Filed Nov. 27, 1956 fla /glad aii; i----l WQZMMM 9 QQQV-H E Emu-$ 343 ".wwvmm mm 2. mm mm w .v Q h. 0 mm mm HF vw 8 s s s .1

V/Ill!!! M; a 47 AA Il a 2,975,679 Patented Mar. 21, 1961 POWER SYSTEM FOR FIREARMS David C. Fletcher, Springfield, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Nov. 27, 1956, Ser. No. 624,708

3 Claims. (Cl. 89-192) (Granted under Title '35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purpose without the payment of any royalty thereon.

This invention relates to firearms and more particularly to power systems for the actuation of the operating mechanisms thereof.

With conventional power systems which are actuated by gases bled from the barrel to energize an operating rod, a terrific impact is given to the operating rod and the parts moved thereby because ofthe high pressure applied by the gases against the operating rod and the short period during which the operating rod can be energized by the gas pressure. In such power systems, the operating rod hasto be energized at the very beginning of the stroke and suflicient energy impressed therein to carry the operating mechanism during the remainder of the operating cycle. As a result, the power stroke has to be relatively short with an extremely high acceleration imparted" thereto.

Attempts have been made to reduce the initial impact, lengthen the power stroke and reduce the acceleration by moving the gas port towards the breech of the barrel to extend the time during which the operating rod can be energized and, thus, permit a reduction in the size of the gas ports to reduce the initial impact. There are also systems which use trapped gases but in all of the systems there remains a considerable impact given to the operating parts and power is not evenly applied during the entire power stroke.

It is, therefore, an object of this invention to provide a firearm power system having a long power stroke of even acceleration and with the forces applied evenly during the entire stroke.

It is another object of this invention to provide for firearms a power system which utilizes gases bled from the firearm to actuate the operating mechanism thereof indirectly.

It is a further object of this invention to provide a firearm power system which is powered by a spring energized by gases bled from the firearm barrel.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a longitudinal cross-sectional view of the power system showing the operating rod and cylinder in normal positions;

Fig. 2 is similar to Fig. 1 but showing the cylinder in forward position and attached to the operating rod and the power spring fully energized; I

Fig. 3 is similar to Fig. 2 but showing the operating rod moved by the cylinder to a position midway of the travel thereof by the bias of the power spring;

Fig. 4 is a view taken along line 44 of Fig. 1; and Fig. 5 is a view taken along line 5-5 of Fig. 2. Shown in the figures is a firearm barrel 12 having a bracket 14 attached thereto at the rear portion. A portion of bracket 14 extends below barrel 12 and provided longitudinally through said depending portion is a bore 16 which slidingly supports an operating rod 18 which reciprocates parallel with the axis of the barrel. The front end of operating rod 18 remains forwardly of bracket 14 as the operating rod reciprocates and provided in the underside of such operating rod adjacent the front end is a transverse notch 20. With operating rod 18 in normal forward position, notch 20 is spaced from bracket 14 approximately the distance which such operating rod travels. Provided on barrel 12 forwardly of bracket 14 and adjacent the front end of operating rod 18 when in normal forward position is an annular ring 22 which may be integral with the barrel or securely fixed thereto. The outer periphery of ring 22 is centered in the axis of barrel 12 and is machined to a smooth finish.

Extending from the bore of barrel 12 to the outside thereof immediately forward of ring 22 is a pair of diametrically-opposed gas ports 26. The outer surface of a portion of barrel 12 extending forwardly from the gas ports 26 is machined concentric to the outer periphery of ring 22 and to a smooth surface to form a bearing portion 28.

Slidingly mounted on bearing portion 28 is a cylinder 32 having a bore which has a diameter approximately the same as the outside diameter of ring 22 and which is machined to a smooth surface so that the sliding contact between such ring and cylinder is substantially gas tight. Provided on the front end of cylinder 32 is a head portion 34 having a longitudinal bore 36 axially therethrough. The diameter of bore 36 is approximately the same as that of bearing portion 28 and is smoothly finished so that the sliding contact between head portion 34 and such bearing portion is also substantially gas tight. If found necessary, a sealing ring can be mounted in suitable annular grooves in head portion 34 and ring 22 to reduce escapement if gases thereby. A compressible coil spring 38 is mounted on hearing portion 28 with the rear end seating against head portion 34. The front end of spring 38 seats against a collar 39 which is mounted to barrel 12 for longitudinal adjustment therealong as by thread means. Spring 38 is designed to bias cylinder 32 rearwardly from the forward position thereof with a force which is sufiicient to operate the mechanism actuated by operating rod 18..

The rear' position of cylinder 32 is determined by the contact of the rear end thereof with bracket 14, and the cylinder has such length that, when the rear end thereof is in contact with the bracket, head portion 34 is positioned forwardly of gas port 26 so that the gases from the bore of barrel 12 may enter cylinder 32 in the expansible chamber therein which is terminated by ring 22 and such head portion to drive such cylinder forwardly to load spring 38.

A lug portion 40 depends from the rear end of cylinder 32 and is provided with a longitudinal hole 42 therethrough to slidingly receive operating rod 18. A lateral slot 44 extends vertically upward into lug portion 40 to traverse hole 42 and is terminated by a semicylindrical portion 46 which is interrupted by the bore of cylinder 32 to form a rectangular orifice 48. Slidably mounted in slot 44 is a latch member 50, which has a top portion arcuately formed to mate with portion 46, and a tab portion 52, which extends upwardly from such top portion to be receivable through orifice, 48 for extension into cylinder 32.

A plug 54 blocks the lower end of slot 44, and a spring 56 is positioned between latch member 50 and such plug to bias such latch upwardly. Provided longitudinally through latch 50 is a bore 58 having a diameter similar to that of operating rod 18 which slidingly passes therethrough, and such bore is so disposed as to tab portion 52 that such tab portion is held clear of the inside of cylinder 32 by the sliding contact of operating rod 18 with such latch. However, latch 50 is receivable into notch 20 when cylinder 32 is in the forward position, When latch 50 is received by notch 20, cylinder 32 is attached to operating rod 18, whereby rearward travel of such cylinder under the bias of spring 38 is transferred to such operating rod, and tab portion 52 extends into cylinder 32.

Provided on barrel 12' so as to be adjacent latch 50 when cylinder 32 is in rearward position is an annular flange 60 having an outside diameter similar to the diameter of cylinder 32 so that such flange is receivable therein. The front side of flange 60 extends rearwardly and outwardly-from the outside perimeter of barrel 12 to form an annular cam portion 62 which is cooperable with an angular portion 64 on the rear side of tab portion 52 for camming latch 50 downwardly to align bore 53 with operating rod 18. Whereby, operating rod 18 is released from cylinder 32 and is free to be biased to normal forward position by a spring 66. Provided in the rear portion of cylinder 32 so as to be positioned forwardly of ring 22 when such cylinder is in forward position is a pair of diametrically-opposed vent ports 68 which permit the escape of the gases trapped in such cylinder when in full forward position.

Operation The power system of the invention operates as follows: A round is fired in barrel 12, and as the bullet passes the gas ports 26, the gases from the explosion enter the gas ports and are received by cylinder 32 in the expansible chamber terminated by head portion 34 and ring 22. As

the gas pressure increases, cylinder 32 is moved along bearing portion 28to compress and load spring 38 until latch 50 is received by notch 20 and the ventports 68. are positioned forwardly of ring 22. whereupon, the gases trapped in cylinder 32 are vented to the atmosphere and the load in spring 38 is permitted to move such cylinder rearwardly as well as operating rod 18 which is attached thereto through latch 50 and notch 20. The rearward movement of cylinder 32 and operating rod 18 is dampened by the limited passageway for the gases from cylinder 32 through the gas ports 26 as the space 'between head portion 34 and ring 22 is reduced, Consequently, the acceleration given cylinderv32 by spring 38 is considerably reduced and thereby the movements of operating rod 18 and the firearm mechanism attached thereto are relativelysmooth. Whenspring 38 has moved operatingrod 18 to the rearward limit of travel thereof, cam portion 62 andi angular portion 64 cooperatetodepress latch and disconnect the operating rod-from cylinder 32 whereupon operating rod 18 is free to be returned to forward position by spring 66. The load of spring 38 and the rate of operation of the power device is regulatable by moving collar 39 along barrel 12.

From the foregoing it is clearly apparent that there is herein provided an improved firearm powerjsystem which applies force evenly to the operating mechanism of the firearm during the. full length of the power stroke, and

- thereby reduces high stresses in the firearm and breakage of operating parts, permits a long power stroke, and which is simple and rugged in construction and positive in operation. L p

Although a particular embodiment of the invention has been described indetail herein, it is evident. that many the bore of the barrel and said cylinder, a spring mounted.

variations maybe devised within the spiritand scope thereof and thefollo wing claims are intended toinclude such variations.

I claim: p I 1. A power system fora firearm having a barrel, and an operating rod biasedfor travel from a rearward toa forward position parallel to the longitudinal axis of the barrel, the power system includinga cylindricalpbearing portion along the outside of the barrel, an annular flange provided around the barrel at the rear end of said bearing portion, a cylinder mounted over the barrel for substantially gas-tight sliding contact with said flange, a head portion terminating the frontend of said cylinder and having a bore therethrough for slidably receiving said bearing portion with; substantially 'gas-tight contact between said head portion and said bearing portionto form between said cylinder and thebarrel an expansible annular chamber, gas ports for bleeding gas pressure from the barrel to said chamber adjacent said flange for moving said cylinder forwardly along said bearing portion, a spring engageable by said cylinder when actuated by the gas pressure, said spring being adapted to store sufiicient energy for actuating the operating rod, adjustment means for regulating the energy storable by said spring, and a latch member mounted on said cylinder for releasably 2. A power system for a firearm having a barrel with a bore and an operating rod biased for travel from a rearward to a forward position parallel to the iongitudinal axis of the barrel, the power system including a cylindrical bearing portion along the barrel, an annular flange provided around the barrel at the rear end of said bearing portion, a cylinder mounted'over the barrel for substantially gas-tight sliding contact with said flange, a head portion terminating the front end of said cylinder and having a-bore therethrough for'slidably receiving said bearing portion with substantially-gas-tight contact between said head portion and said bearing portion to form anexpansible gas vchamber between the barrel and said cylinder to provide communication between the bore and'said chamber adjacent said flange, a compressible coil spring mounted over the barrel and having rear con tact with said head portion, said spring being adapted to store sutficient energy for actuating the operating rod, adjustment means disposed between the front end of said spring and said barrel for regulating the energy storable by said spring when said cylinder is moved thereagainst by the gases discharged into said chamber from the bore, a latch member mounted on said cylinder'for releasably connecting said cylinder to the operating rod to transfer the energy in said spring to the operating rod for actuation thereof after said spring is energized, and a cam portion disposed'on the barrel for cooperation said latch member to'release the operating rod from said cylinder when the operating rod is in the rearward position. i 3. A power system for a firearm having a barrel with a bore and an operating ,rod biasedfor travel from a portion, a cylinder-mounted over the barrel for substantially gas-tight sliding contact with said flange, a head portionterminating the front end of said cylinder and having a bore therethrough for slidably receiving said bearing portion with substantially gas-tight contact between said head portion and said bearing portion, an expansiblechamber'forrned between said b-arreland said cylinder by said flange and saidhead portion, gas ports adjacent said flange to providefcommunication between over the barrel and having rear contact withsaid head portion, said spring being adapted to store su flicient energy for actuating the operating rod, adjustment means disposed between the front end of said spring and said barrel for-regulating the energy storable by said spring, a latch member mounted 'on' said;:.cylirider.for releasably connectingsaid' cylinder. to the-operatingirod to transfer therenergy in said spriugtto the operatingsrodifon actuation 5 6 7 thereof after said spring is energized, a cam surface dis- References Cited in the file of this patent posed on the barrel for cooperation with said latch mem- UNITED STATES PATENTS her to release the operating rod from said cylinder when the operating rod is in the rearward position, and ports 1'563285 Netsch 1925 in said cylinder for venting therefrom excessive gases dis- 5 2'186969 Green 1940 charged into said chamber after the operating rod is FOREIGN PATENTS attached by said latch to said cylinder to permit actua 27972 Great Britain 1911 therwf by said SPring- 228,678 Switzerland Dec. 1, 1943 

